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In this June 3, 2010 photo, 1st Lt. Jay Park participates in pre-deployment cognitive testing at the Fort Campbell Army base in Fort Campbell, Ky. Soldiers from the Army's 52nd Ordnance Group based at Fort Campbell have undergone hours of exhaustive cognitive testing in the military's first-of-its-kind study of mild traumatic brain injury. This focus on the soldiers who find and destroy the powerful and deadly weapons is part of a larger effort by the military this year to better track and treat mild brain injuries. (AP Photo/Josh Anderson)
/ AP